@article{oai:jaxa.repo.nii.ac.jp:00022568,
 author = {Nagai, Shin and Ishii, Reiichiro and Suhaili, Affendi Bin and Kobayashi, Hideki and Matsuoka, Masayuki and Ichie, Tomoaki and Motohka, Takeshi and Kendawang, Joseph Jawa and Suzuki, Rikie},
 issue = {23},
 journal = {International Journal of Remote Sensing},
 month = {Nov},
 note = {We examined the usability of daily green–red vegetation index (GRVI) observations from the Terra and Aqua Moderate Resolution Imaging Spectroradiometer satellite on cloud-free days for monitoring ecosystem changes in Bornean tropical forests at a 500 m spatial resolution over 11 years (2003–2013). The number of observational days of cloud-free GRVI data in the southwest monsoon period (May–October; 1–5 days/month) was greater than that in the northeast monsoon period (November–April; 0–2 days/month). Spatial variation in the observation frequency was noticed, with Terra (morning) and Aqua (afternoon) data showing different geographic distribution patterns of cloud-free data. The observation frequency in the western Kalimantan mountains (Sarawak and Sabah) was 1–2 days/month greater than that in the eastern mountains (Kalimantan). The quality of cloud-free GRVI data was validated by using sky images taken at the same time as the satellite observations and canopy surface images in a tropical rainforest. In oil palm and acacia plantations and peatlands, which were mainly distributed in coastal regions of Sarawak and West and Central Kalimantan, the cloud-free daily GRVI value fell below zero owing to deforestation and forest degradation caused by forest fire and increased with replanting and vegetation recovery. These results indicate that daily cloud-free GRVI data from multiple satellites collected at different times of the day are required for accurate monitoring of intra- and interannual phenological variation and forest degradation attributed to changes in climatic conditions and deforestation caused by human activities in tropical ecosystems., Accepted: 2014-08-28, 資料番号: PA1510071000},
 pages = {7910--7926},
 title = {Usability of noise-free daily satellite-observed green–red vegetation index values for monitoring ecosystem changes in Borneo},
 volume = {35},
 year = {2014}
}